Textile fiber sizing agents

ABSTRACT

REACTION OF A CROSS-LINKED, THIN-BOILING STARCH WITH A POLYCARBOXYLIC ANHYDRIDE YIELDS AN EFFECTIVE WARP SIZE COMPOSITION.

United States Patent 3,661,895 TEXTILE FIBER SIZING AGENTS Felix Joseph Germino, Palos Park, Joseph Frank Stejskal, Brookfield, Edwin Hans Christensen, La Grange Park, and Francis Ervin Kite, Riverside, Ill., assignors to CPC International Inc. No Drawing. Filed Oct. 1, 1969, Ser. No. 862,969 Int. Cl. C131 1/08 US. Cl. 260-233.5 23 Claims ABSTRACT OF THE DISCLOSURE Reaction of a cross-linked, thin-boiling starch with a polycarboxylic anhydride yields an effective warp size composition.

This invention relates to a process for the preparation of relatively non-viscous starch derivatives. It also relates to the preparation of starch derivatives which are especially useful in the treatment of yarns to improve the physical properties thereof.

Starch and starch derivatives are used by the textile industry as a coating size to strengthen warp yarns and improve their resistance to abrasion during weaving. This process of sizing often is called slashing. Yarns spun from staple fibers such as cotton are slashed with starch solutions to improve the strength and abrasion resistance of the yarn and to reduce the fuzz of the yarn by cementing the protruding surface fibers to the body of the yarn. The strength of the yarn is increased -30% by this action, and the increased stiffness facilitates handling in starting the Warp through the loom. To accomplish these actions, size films are applied as a thin coating on the surface of the spun yarn and should penetrate the yarn only far enough to provide satisfactory adhesion of the size film. If the size permeates the spun yarn, the yarn will be too stiff. The amount of size added to spun yarns is usually 10-15% of the weight of the unsized yarn, although smaller amounts can be used.

Yarns composed of continuous filaments are slashed with starch, chemically modified starches, water-soluble synthetic polymers, or mixtures of these materials. The filament yarns are sized to provide abrasion resistance and also to cement the individual filaments together. The filaments are cemented to prevent the formation of fuzz balls which occur when a single filament breaks and is pushed back along the body of the yarn. If the filaments are not cemented together, the broken filaments accumulate until they cause sufiicient entangling to actuate the stop-motion mechanism of the loom. Materials used to size filament yarns thus must penetrate the yarn completely. The amount of the size added to filament yarns is 3-5 of the weight of the unsized yarn, and this small amount does not cause excessive yarn stiffness.

Size solutions for warp yarns must have many specific properties. They must be inexpensive; they must be easily prepared; they must be characterized by a uniform viscosity and solids content. Because the slashing operation, like most other industrial processes, is run at maximum speed to minimize labor and overhead costs, size solutions must be relatively free of foaming tendencies; and they should desirably be relatively non-viscous so as to permit the above speedy operation of the slashing process.

A wide variety of starch derivatives, in addition to starch itself, have been reported as useful for warp sizing. These include cationic starches, dextrins, acid-modified starches, hydroxyethyl starch, canboxymethyl starch, oxidized starches, starch acetate and starch phosphate. Acid-modified corn starch in particular has found wide usage for this purpose, the bulk of it going into the pro- Patented May 9, 1972 ice duction of cotton goods and cotton-synthetic blends. Acid-modified starch is superior to starch itself in warp sizing, and in many other textile applications, largely because of its reduced viscosity. While cross-linked starches are effective warp sizes, because of the good abrasion resistance that accrues from the effect of swollen but unbroken starch granules, they must be used at a relatively high solids content and they result in a somewhat brittle fiber; furthermore in some cases there is a problem of setback.

A principal object of the present invention is the preparation of a warp size composition.

Another object of the present invention is the preparation of a relatively non-viscous warp size composition.

Still another object of the present invention is the preparation of such a warp size composition which is derived from an acid-modified and/ or oxidized starch.

Still another object of the present invention is the preparation of such a warp size composition which is a crosslinked starch.

These and other objects of the present invention are accomplished by a process comprising reacting a polycarboxylic anhydride with a cross-linked, thin-boiling starch. In a preferred embodiment the reaction is carried out at a pH of from about 8.0 to about 10.0.

The starch used as the ultimate raw material may be of any type. It may be a root or root-type starch such as tapioca, potato, waxy maize, sago, waxy sorghum, sweet potato or arrow root starches. It may also be a cereal starch such as corn, wheat, rice, sorghum or high amylose corn starch. Because of its ready availability, corn starch is preferred.

The thin-boiling starch may be an acid-modified starch or it may be an oxidized starch.

The acid-modified starch may be prepared by any of the several well-known methods disclosed in the prior art. The methods disclosed in US. 2,967,178 are especially suitable. One such method involves heating at a relatively low temperature a mixture of starch and hydrochloric acid at a pH within the range of from about 1.0 to about 2.5. The reaction is carried out for a period of time so as to produce a product of approximately intermediate viscosity between that of starch itself and water. A preferred way of expressing the fluidity of an acid-modified starch is in terms of its Scott viscosity, the determination of which is described in II Whistler and Paschall, Starch: Chemistry and Technology 604-5 (1967). The acid-modified starches herein should have a Scott viscosity within the range of from about 55 grams/40 seconds to about 25 grams/4O seconds. Ordinary corn starch has a Scott viscosity of 12 grams/70 seconds. Ordinarily, the time of the acid modification reaction is within the range of from about 2 to about 10 hours; the use of a weaker acid medium requiring a longer reaction time and a stronger acid medium permitting a shorter reaction time. The temperature of the reaction is generally within the range of from about 20 C. to about 55 C.

Sulfuric acid may be used in place of the hydrochloric acid. Other mineral acids can be employed, but in general the preparation of an acid-modified starch utilizes either hydrochloric acid or sulfuric acid. I

Oxidized starch suitable for use herein may be prepared by reaction of starch with alkaline hypochlorite. The reaction is well known and is described in the Whistler et al. text above at 23 8-42.

The cross-linking step can be carried out in any of the several known methods for accomplishing this type of reaction with starch. The cross-linking, frequently termed cross-bonding, is accomplished by joining separate starch molecules through their hydroxyl groups and any molecule capable of reacting with two or more hydroxyl groups will serve this purpose. Such cross-linking agents ordinarily react with the starch by means of an etherification or an esterification reaction. Epichlorohydrin, butadiene dioxide, and aldehydes are examples of cross-linking etherification agents; representative examples of cross-linking esterification reagents include phosphorus oxychloride, diisocyanates, cyanuric chloride, sodium trimetaphosphate and sodium hexametaphosphate. Since all of these reagents, when reacted with starch in the ungelatinized granule form, result in a cross-linking of the hydroxyl groups of the starch molecule, they are referred to hereinafter as cross-linking agents, these being either crosslinking etherification or cross-linking esterification agents.

The amount of cross-linking agent which should be used herein is such as to produce a cross-linked starch having a Scott viscosity within the range of from about 55 grams/ 40 seconds to about grams/40 seconds. When the cross-linking agent used is sodium trimetaphosphate, for example, an appropriate amount is within the range of from about 0.3 to about 0.7% based on the weight of dry starch.

The cross-linking reaction is carried out simply by mixing the acid-modified starch and cross-linking agent in an aqueous medium, maintaining the temperature at 5-60 C. until the product has the desired viscosity (Scott). Neither the pH nor the temperature should be permitted to get so high as to cause gelatinization.

The acylation reaction is accomplished by reaction of the starch with a polycarboxylic anhydride. This also involves an esterification reaction with the hydroxyl groups of the starch molecules. The polycarboxylic anhydrides include aliphatic, alicyclic and aromatic polycarboxylic anhydrides, principally the dicarboxylic anhydrides, and preferably maleic anhydride and succinic anhydride. Others include glutaric, phthalic, trimellitic, itaconic and citraconic anhydrides. The acylation reaction should preferably follow the cross-linking reaction although, in some instances, the order of these reactions may be reversed; in some instances it will be desirable to permit them to occur simultaneously.

The amount of polycarboxylic anhydride used is such as to yield a product having a degree of substitution (D.S.) of at least about 0.02. The upper limit of D5. is about 0.10. The BS. value reflects the concentration of polycarboxylic acid units per anhydroglucose unit in the starch chain, 3.0 being the maximum D.S. because there are 3 hydroxyl groups in each anhydroglucose unit. An appropriate amount of maleic anhydride (when it is the polycarboxylic anhydride used), for example, is within the range of from about 1.0% to about 10.0% based on the weight of dry starch.

The reaction of the cross-linked, acid-modified starch with the polycarboxylic anhydride involves merely mixing them in an aqueous medium at a temperature within the range of from about C. to about 60 C. The reaction mixture generally is alkaline for best results and in a particularly preferred instance the pH is within the narrow anhydride linkage with formation of an ester between a starch molecule and a polycarboxylic acid molecule and formation of a sodium starch carboxylate. As this reaction proceeds the acidity may be controlled by addition of aqueous sodium hydroxide.

The polycarboxylic anhydride reactant may be added to the reaction mixture as such, e.g., as briquettes, or as a solution in acetone, or chloroform, or some other such inert solvent. Acetone is preferred.

The reaction proceeds better in concentrated media and it is preferable that the reaction mixture contains as little water or other suspending media as required to permit convenient handling. A reaction mixture containing 55% water produces a very efiicient reaction. Less concentrated mixtures, i.e., containing 70-80% water, are nevertheless suitable for the purposes herein.

The preparation of the compositions of this invention is illustrated by the following specific examples:

EXAMPLE I Preparation of acid-modified starch A 41% aqueous starch slurry is treated at 53 C. with 55% aqueous sulfuric acid for 7 hours. The product is neutralized with 6% aqueous sodium hydroxide to a pH of 4.5; the neutralized mixture has a Scott viscosity of 35 grams/ 57 seconds and a fluidity of 48.

EXAMPLE II The procedure of Example I is repeated using a corresponding amount (so as to produce the same pH) of hydrochloric acid. The resulting product, upon neutralization to a pH of 4.5 with 12% aqueous sodium carbonate, is found to have a Scott viscosity of 35 grams/ 54 seconds and a fluidity of 48.

EXAMPLE III A 41% aqueous starch slurry (100 parts) is treated at 60 F. with 2.6 parts of chlorine in the form of an aqueous alkaline solution containing 13.8% chlorine and 4.2% sodium hydroxide. After 2 hours the reaction mixture has a Scott viscosity of 40 grams/54 seconds. The product is neutralized to a pH of 6.1 with aqueous sulfuric acid, then treated with 0.4% of sodium bisulfiate.

EXAMPLE IV A solution of pounds of sodium hydroxide in 600 gallons of water is added to 25,000 pounds (D.S.) of the above acid-modified starch and stirred while adding a solution of pounds of sodium trimetaphosphate in 300 gallons of water. The temperature of the mixture is maintained at 4952 C. While stirring for 8 hours. The resulting cross-linked product has a Scott viscosity of 25 grams/72 seconds.

EXAMPLE V A mixture of 100 grams of the acid-modified starch product of Example I is mixed with parts of a 0.6% aqueous sodium hydroxide solution and 0.04 part of epichlorohydrin. The resulting slurry is stirred for 16 hours at a temperature of 2530 C. to yield the desired crosslinked acid-modified starch.

EXAMPLE VI A mixture of 6,353 parts (D.S.) of the cross-linked acid-modified starch obtained as in Example 1V is treated portionwise, with a solution of 212 parts of maleic anhydride in 424 parts of acetone. The pH is maintained at about 9.0 by the addition of aqueous sodium hydroxide. The desired reaction is complete within a matter of minutes after the addition of the last portion of maleic anhydride whereupon the product is neutralized to a pH of 7 by the addition of aqueous sulfuric acid. The resulting product has a D8. of 0.04.

EXAMPLE VII The procedure of Example V is repeated using succinic anhydride instead of maleic anhydride. The resulting product has a D8. of 0.05.

The application of the product of this invention to fibers ordinarily is accomplished by means of a pasted or cooked aqueous suspension containing from about 0.5 to about 2 pounds of product per gallon of slurry.

As noted earlier, the pH at which the reaction with the polycarboxylic anhydride is carried out is an important factor in the preparation of a superior Warp size composition. When maleic anhydride is used as the polycarboxylic anhydride the optimum pH is 8.8 and accordingly it is preferred to carry out this reaction at a pH of from about 8 to about 9. At a pH of 10, however, although viscosity is higher, e.g. 700 centipoises at 8% solids and F., the product is very effective, a relatively small amount being required to supply good warp size characteristics. The resulting product has a Brookfield viscosity of 400 centipoises at 12% solids and 190 F.; furthermore, such product is characterized by a relatively high degree of viscosity stability. When succinic anhydride is used as the polycarboxylic anhydride the optium pH is 9.5.

Products prepared as in Examples V and VI when tested for their effectiveness as sizing agents on a 65/35 polyester-cotton blend, at an add-on level of 12%, develop no problems of foaming, skinning, congelation or setback. Furthermore, they provide good abrasion resistance to the treated fibers.

All parts herein, unless otherwise expressly stated, are by weight.

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall Within the scope of the invention.

We claim:

1. A process for preparing a relatively non-viscous starch derivative comprising reacting 1) an acid-modified starch having at Scott viscosity within the range of from about 55 grams/40 seconds to about 25 grams/40 seconds or a hypochlorite-oxidized starch with a (2) cross-linking etherification reagent or a cross-linking esterification reagent, to form a cross-linked starch, and reacting said cross-linked starch with a polycarboxylic anhydride at a pH of from about 8.0 to about 1 0.0, the amount of said polycarboxylic anhydride being such as to produce a product having a degree of substitution of from about 0.02 to about 0.10.

2. The process of claim 1 wherein the thin-boiling starch is an acid-modified starch.

3. The process of claim 1 wherein the thin-boiling starch is an oxidized starch.

4. The process of claim 1 wherein the step of crosslinking is effected by sodium trimetaphosphate.

5. The process of claim 1 wherein the step of crosslinking is effected by epichlorohydrin.

6. The process of claim 1 wherein the step of crosslinking is effected by phosphorus oxychloride.

7. The process of claim 2 wherein the acid-modified starch is prepared by heating a mixture of starch and hydrochloric acid at a temperature within the range of from about 5 C. to about 55 C., at a pH within the range of from about 1.0 to about 3.5, for 2-10 hours.

8. The process of claim 2 wherein the acid-modified starch is prepared by heating a mixture of starch and sulfuric acid at a temperature within the range of from about 6 5 C. to about C., at a pH within the range of from about 1.0 to about 3.5, for 2-10 hours.

9. The process of claim 1 wherein the polycarboxylic anhydride is an aliphatic carboxylic anhydride.

10. The process of claim 1 wherein the polycarboxylic anhydride is an alicyclic carboxylic anhydride.

11. The process of claim 1 wherein the polycarboxylic anhydride is an aromatic carboxylic anhydride.

12. The process of claim 1 wherein the polycarboxylic anhydride is maleic anhydride.

13. The process of claim 1 wherein the polycarboxylic anhydride is succinic anhydride.

14. The process of claim 1 wherein the polycarboxylic anhydride is an aliphatic carboxylic anhydride.

15. The process of claim 14 wherein the step of crosslinking is effected by sodium trimetaphosphate.

16. The process of claim 14 wherein the step of crosslinking is effected by epichlorohydrin.

17. The process of claim 14 wherein the step of crosslinking is effected by phosphorus oxychloride.

18. The process of claim 15 wherein the acid-modified starch is prepared by heating a mixture of starch and hydrochloric acid at a temperature within the range of from about 5 C. to about 55 C., at a pH within the range of from about 1.0 to about 3.5 for 2-10 hours.

19. The process of claim 12 wherein the acid-modified starch has a Scott viscosity of from about 55 grams/40 seconds to about 25 grams/40 seconds.

20. The relatively non-viscous starch derivative prepared by the process of claim 1.

21. The relatively non-viscous pared by the process of claim 14.

22. The relatively non-viscous pared by the process of claim 4.

23. The relatively non-viscous pared by the process of claim 15.

starch derivative prestarch derivative prestarch derivative pre- References Cited UNITED STATES PATENTS 2,461,139 2/1949 Caldwell 260234 2,935,510 5/1960 Wurzburg 2602333 2,938,901 5/1960 Kerr et a1. 260233.5 2,967,178 1/11961 Kerr et al. 260233.5 3,238,193 3/1966 Tuschhoif et al. 260233.5 3,467,647 9/1969 Benninga 260209 FOREIGN PATENTS 789,003 7/1968 Canada 260-233.3

DONALD E. CZAJA, Primary Examiner M. I. MARQUIS, Assistant Examiner U.S. Cl. X.R.

106-213; ll7-139.5 C; 260--233.3 R 

